1. Field of the Invention
The present invention relates to an auxiliary device for use in the exchanging of a filter in a clean room. The present invention also relates to a method in which the auxiliary device is used to exchange the filter.
2. Description of the Related Art
High-tech industries presently demand high-purity production environments to ensure the quality and yield of production products. In this respect, the precision, purity, and asepsis of the production line are especially important.
These characteristic requirements of a production environment have been greatly improved by the introduction of the clean room. Clean rooms include the Bio Clean Room (BCR) and the Industrial Clean Room (ICR). The Bio Clean Room (BCR) is used in the medical field for preventing bio-contamination during the manufacturing of medicine, drugs, and foods, and during genetic engineering, etc. The Industrial Clean Room (ICR) is used in the more industrial fields for preventing particles from contaminating such products as semiconductor devices, precise machinery, raw materials, etc.
The semiconductor device fabrication process requires a clean room in which a down stream laminar flow is formed in a production line in order to remove particles which would otherwise have an enormous adverse effect on the performance of the final semiconductor devices and thus, on the production yield.
The Down Stream Laminar Flow Type of clean room is good for quickly removing the particles generated by the various equipment in the production line, by the various materials that are used in the manufacturing process or by operators of the production line. Various methods of developing a down stream laminar flow are being developed along with the continuous development of the make-up of the production line and its maintenance.
The structure and function of a clean room which forms a down stream laminar flow thereinside will next be described referring to FIG. 1.
As shown in FIG. 1, a grating 14 having a plurality of holes is installed on a frame 12 which is set a certain distance above the bottom of the clean room 10. The clean room is thus divided into an upper portion and a lower portion by the grating 14.
Above the grating 14 is a production line 16 comprising the equipment for fabricating semiconductor devices (not shown in the figure for the sake of clarity). On the other hand, below the grating 14 is an auxiliary facility for assisting the fabrication equipment (also not shown in the figure) and a circulation pan 18 for circulating the air inside the clean room 10.
The circulation pan 18 induces air from the upper portion of the clean room 10 to the lower portion thereof by suction and then recirculates the air to the production line 16 through a passage 20 defined in the sidewall of the clean room 10.
Meanwhile, a plurality of filters 22 are installed above the production line 16 for filtering the air. These filters 22 are supported by a filter frame 24. The air is forced through the filters 22 by the pressure formed by the circulation pan 18 and is then directed into the production line 16. The air passing through the filters 22 and directed downwards into the production line 16 passes through the holes of the grating 14 to thereby form a down stream laminar flow.
The particles continuously generated inside the production line 16 are discharged toward the lower portion of the clean room 10 by the down stream laminar flow in order to maintain highly pure state of the clean room 10.
In the meantime, when a filter becomes damaged or contaminated enough, the particles in the air are not filtered by the damaged or contaminated filter 22. This contaminated air spreads quickly, and adversely affects the formation of the down stream laminar flow. As a result, the production line 16 is contaminated.
In order to prevent this problem, the filters 22 are regularly inspected. Any filter found to be damaged is replaced. However, if the filter is replaced while the air is continuously circulated, a large amount of contaminated air is induced into the production line 16 through an open area at the place where the filter has been removed. Accordingly, the production line 16 will become contaminated.
A conventional method of exchanging a damaged filter has been used in an attempt to prevent such a contamination of the production line 16 from occurring. Referring now to FIG. 2, in the conventional method, a curtain of anti-electrostatic vinyl 26 is hung between the filter frame 24 and the grating 14 at that portion of the filter frame 24 which supports the filter to be exchanged. The ends of the curtain of anti-electrostatic vinyl 26 adjacent the grating 14 and the filter frame 24 are sealed with adhesive members 28, respectively. Then, the damaged filter 22 is replaced by first removing the damaged filter into the space above the filter frame 24.
However, when the damaged filter 22 is replaced, the air existing in the space above the filter frame 24 moves toward the open area due to a pressure differential existing above and below the filter frame 24.
Unfortunately, air passing within the curtain of anti-electrostatic vinyl 26 is under such pressure that it separates the seals at the respective ends of the curtain of anti-electrostatic vinyl 26. The induced, non-filtered air spreads through these openings in the seals and contaminates the production line 16.
Therefore, the conventional method of exchanging a filter 22 requires the various operating portions of the production line 16 to be first shut down. Further, the method is carried out while the air circulation is also shut down. Afterwards, the production line facilities must be restarted. Accordingly, carrying out the conventional method of exchanging a damaged or contaminated filter results in a great reduction in the productivity of the line 16.